This invention relates to irrigation systems and, more particularly, to a control device for controlling the flow of irrigation water between an inlet and an outlet thereof comprising, a hollow body having an inlet thereto and an outlet therefrom; a rotating drive positioned within the body; and, flow control means disposed within the body between the inlet and the outlet and driven by the rotating drive for varying the volume of water discharged through the outlet to areas watered by a sprinkler head connected to the outlet without changing the pressure of the water.
Irrigation systems are probably one of the least improved areas of technology. While electronics, for example, is constantly under a state of improvement and innovation, irrigation sprinklers and their associated control systems go for long periods with virtually no functional changes whatsoever. For years, the state of the art was an upward-facing orifice screwed onto the end of a garden hose. Later, oscillating sprinklers (also fastened to the end of a garden hose) became popular. A major step change in sprinkling technology came with the introduction of the impulse sprinkler. As depicted in FIG. 1, such a sprinkler 10 revolves in a circle as symbolized by the arrow 12 emitting a stream of water 14. A variation of the impulse sprinkler allows the sprinkler to revolve back and forth over an arc of a circle as set by adjustable stops.
A more recent improvement to the sprinkler art is the low-precipitation sprinkler head. While the impulse sprinkler head typically requires a large volume of water at high pressure to operate, the low-precipitation sprinkler heads incorporate a water-driven turbine drive to slowly turn the output nozzle portion which emits fine streams of water. With such heads, an adobe-soil hillside such as found in many areas of California can be watered with virtually no runoff (i.e. wasted water) as occurs with high-volume prior art sprinkler heads as described above.
To water large areas which are unwaterable with a single sprinkler head attached to the end of a garden hose (and for added convenience) the prior art devised sprinkler systems wherein a plurality of sprinkler heads are attached to the branches of a system under the control of one or more manual or electrically/electronically controlled valves. The introduction of plastic water pipe greatly simplified the installation of such systems and lead to their general adoption in dry areas requiring constant artificial irrigation such as the southwestern areas of the United States. Typically, the branch pipes from the valves to the sprinkler heads are buried in the ground with riser pipes extending up to the exposed sprinkler heads.
Whether it is a single sprinkler head mounted on the end of a garden hose or a sprinkler system comprising multiple sprinkler heads, all these prior art irrigation approaches suffer from a common problem as depicted in FIG. 1. Within the area 16 being watered, the water requirements for proper irrigation are not constant. For example, there may be a dry spot 16a requiring more water than the rest of the area 16. In the prior art, there are two "solutions" to the problem--neither of which is really a solution. If the area 16 is watered the proper amount, the dry area 16a is not watered sufficiently. If the dry area 16a is watered the proper amount, the rest of the area 16 is overwatered. Thus, the user is placed on the horns of a dilemma. Either waste water (in an area that is typically in a drought condition) and possibly kill plants by overwatering or possibly kill plants from underwatering.
While many prior art sprinkler heads contain an adjustment for the flow volume out, they do so at a sacrifice of the pressure and flow rate as well. As a consequence, the head no longer covers the same area. Thus, peripheral areas that were previously watered by the head are no longer watered at all in order that the area close to the head is watered less. This, of course, has a major drawback in that no matter how long the head is left on, the areas no longer reached by the emitted stream will never be watered (barring flooding of the area as a result of total water volume emitted--a totally wasteful approach).
One solution would be to have a single rotating sprinkler head that revolved more slowly where more water was needed so that a greater volume of water would be discharged where more water was needed.
Another solution would be to have a multiple sprinkler head system wherein heads in areas requiring less water could be set to have the same force and pressure as other heads (thus covering the same area) yet emit a lower total volume of water.
Contemporary sprinkler systems suffer from additional problems, particularly under the drought conditions that seem to be facing many parts of the country more and more as population densities (and corresponding demands on the limited water available) continue to rise. For example, unless a sprinkler system employs the low precipitation sprinkler heads as described above, much of the irrigation water applied to the soil simply runs off. In large open fields this is not a problem. In urban settings, however, what runs off the lawn and planting areas simply runs down the driveway and walkways into the gutter and into the storm drains and is completely wasted. Unfortunately, since the low precipitation sprinkler heads are typically more expensive than a simple orifice opening sprinkler head or a plastic impulse sprinkler head, most installations employ the lower-cost, higher-discharge heads.
Another typical problem the inability to provide proper action and coverage with the number of sprinkler heads operating at a time under the flow conditions typically available. Most residences have a 3/4" or 1" line into the house. Usually, the supply line to the sprinkler valve manifold is no more than 3/4" and it would be unusual to find that the branch lines from each valve to the various sprinkler head connected to it are greater than 1/2". In a lawn area where perhaps six or eight simple orifice opening sprinkler heads are connected to a single valve and operate simultaneously, the flow rate (actually a spray pattern) of the heads is of such a low volume per unit time that the coverage is generally adequate. Where several larger orifice impact sprinkler heads are operated simultaneously, however, one may find that unless the line pressure is very high, the heads do not operate well. For one, they may not cycle consistently between their two modes of operation when covering an arc of less than 360.degree.. For another, their deflected spray pattern may be insufficient to water properly close to the head such that only any annular area at the end of the main stream is properly watered.
Wherefore, it is an object of this invention to provide a single rotating sprinkler head that revolves more slowly where more water is needed so that a greater volume of water is discharged where more water is needed.
It is another object of the invention to provide a sprinkler head for use in a multiple sprinkler head system wherein heads in areas requiring less water can be set to have the same force and pressure as other heads while emitting a lower total volume of water.
It is yet another object of the invention to provide a device which can be mounted in-line with one or more conventional high-precipitation sprinkler heads to provide low-precipitation operation thereof so as to prevent wasteful runoff of irrigation water.
It is still another object of the invention to provide a device which can be mounted in-line with one or more conventional high-precipitation sprinkler heads to provide proper operation thereof in the presence of low supply pressures and the like.
Other objects and benefits of the invention will become apparent from the description which follows hereinafter when taken in conjunction with the drawing figures which accompany it.